Japanese laid-open utility model publication No. 61-84658 discloses a power tool in which a motor-side terminal and a power-side terminal are connected to each other via a plug-and-socket type connection. According to the known power tool, a plug-type terminal which is provided on a power-supply wiring assembly side to be connected to a power switch is inserted into a socket-type terminal which is provided on a motor side to be connected to a coil terminal of a stator.
In a known power tool, outside air is introduced into the internal space of a housing in order to cool a motor. For example, if the known power tool is represented by a disc grinder which is used to grind or polish metal materials, metal chips generated by the operation may possibly enter into the internal space of the housing together with outside air. If the terminal connection is loosened due to vibration or other causes during grinding or polishing operation and part of the terminal connection is exposed to the internal space, metal chips which have entered the internal space may come into contact with the exposed portion and cause leakage of current. Therefore, the known terminal connection has a problem in dust resistance and further improvement is required in this point.